Phone Volume!

I have a Zumo 550 with an Autocom system,bluetooth dongle,ultimate ear earphones etc.
My problem is for some reason when i receive a phonecall i can't turn the volume down to the extent it hurts my ears.(usually when the wife rings)
I have turned off the volume on the phone,the keypad on the zumo and the settings in the zumo directory and the volume does,nt alter

Does anyone have any ideas. (The Zumo unit has just been replaced as i had lots of trouble with with the original unit)

Thanks in advance....

The incoming volume is controlled via the BT dongle, to lower your system the easiest way would be to have your main system returned back to us so we can modify your incoming phone volume so that it does not come through as loud.

Rich